Just put water meth injection on to my truck anyone know the best mix for it.

 

Max power or max cooling? I run 50/50 when I want power, daily driving I'm running 25% meth. You need some meth in there even if you're just trying to keep thing cool, otherwise the water puts out the fire too easily. I've found I can run almost as much water/meth at 25% as at 50%, but with straight water you have to cut the flow way back.

 

I agree with Dave. 25% works well and allows you to start injecting around 15-18 psi boost with no problems.
If you don't want to buy Methanol fuel, use winterized washer fluid...it's 20% meth as best I can tell.

RJ